1. Field of the Invention
The invention relates generally to providing comfortable climate in living quarters while providing freshwater from the atmosphere in regions suffering from freshwater shortage compounded with extended periods of extremely high temperature and very high humidity.
2. Summary of the Invention
Extreme heat in tropical and semi-tropical regions is usually accompanied by extremes of high humidity, especially at low altitude where bayous, marshlands, swamps, shallow lakes, heavy vegetations, and forests are abundant; tropical islands, such as the islands of the Caribbean Sea; arid land and deserts nearby oceans shorelines or seashores; such as the regions East of the red Sea and West of the Gulf on the Arabian Peninsula. Generally, natural freshwater resources are scarce or limited in very hot and humid arid areas by or near shorelines due to low precipitation and rainfall and high salinity of underground water.
Shortage in supply of potable water and freshwater is increasing at a vast rate as deserts expand and overtake fertile land and as many of the natural ground waterresources are being depleted. Shift in global weather patterns throughout time resulted in a drop in the rate of rainfall in many populated areas. In addition, large cities are expanding at a fast pace, swallowing neighboring villages and small towns, leading to drastic change in the lifestyle of inhabitants of regions of extreme high temperatures and humidity. With the shift from rural to urban lifestyle, people are forced to live in crowded housing and congested apartments with no or little opportunities to fresh air, thus suffering from stuffiness, heat and humidity, and being more exposed to an increasing shortage of freshwater supply.
Accordingly, there is a great need in most new residential developments in hot humid regions for easy access to sufficient freshwater supply as well as for means to cool and dry indoor atmosphere to a level that is barely adequate for leading a healthy and relatively comfortable existence in the dwellings of people with limited resources. Luckily, the lifestyle of people in most of the hot humid regions is such that residents do not require great reduction in temperature or humidity to lead a comfortable life in their housing or work environment.
Water condensation from humid hot air takes place as part of any air conditioning or air drying cycle employed in the wide spread commercial devices used in apartment buildings, residential homes, industrial facilities and commercial establishments. Usually the condensate from such devices drips out and is customarily disposed of as useless wastewater. Naturally, collection and treatment of the drained condensate can provide a continuous source of freshwater.
Air-drying equipment are of widespread use in cold regions to dehumidify air in basements that are commonly used for storage of fruit and perishable food products that do not require refrigeration and can be kept for long time in dry cool space. Dehumidifiers are also used in cold regions as well as hot humid regions in spaces used for storage of clothes and household furniture that can be affected by humidity and subsequent mold buildup. Air-drying equipment are also used in drying of manufacturing environment wherein wet raw material and stock material saturated with moisture for ease of production; such as the case in paper and wood fabrication. Often relatively dry air is required for maintenance of the quality of some products that may be affected by increase in humidity over a set level even for a short period.
The quantity of wastewater produced by dehumidifiers depends on the humidity of ambient air and could reach large quantities in regions of extremely high humidity and high temperature wherein water is usually scarce. In case of air conditioning equipment used for air-cooling and ventilation, the amount of water condensate depends on the capacity of equipment, the temperature setting inside and the temperature and relative humidity outside the building and accordingly the rate of condensation changes with the daily and seasonal variation of the local weather. In any case, air conditioning and dehumidification equipment produce on the long run substantial quantities of water when there is a need to cool or dry the air.
The onrush of vast developments of water vapor condensation, air conditioning and removal of humidity from air whether to maintain a comfortable living environment or for various industrial applications provide the possibility to produce high quality freshwater from ambient air of different humidity levels. Techniques to produce water by condensation of water vapor entrained in ambient air are expected to be economically competitive with traditional methods of production of water from other resources. For example, the effort to condense air humidity to obtain a specific quantity of water is much less than the effort to be expended in obtaining the same quantity of freshwater by desalination of seawater or underground brackish water.
People living in regions of high temperature and high humidity can resort to dehumidifiers to extract water from air while drying ambient air to maintain a comfortable living environment at their homes or work places. Hot and dry air is easier to tolerate since high humidity increases the heat index and the human sensation of hot weather. The dry air exhaust of dehumidifiers is less hot than ambient temperature if the equipment is modified to prevent heat pick up by dried air as it leaves the equipment.
Accordingly the possibility of combining freshwater production and easing of weather heat distress inside dwellings will increase the return from equipment that can condensate water vapor from ambient air specially in areas of extreme or relative deprivation from life necessities by supplying the residents with direly needed freshwater while providing them with some relief from the harsh weather. Coolness of the dwellings will provide inhabitants with physical comfort and reduce their need for water intake.
Additionally, there are many resorts and vacationing places in hot, humid regions deprived from drinking water and freshwater since they are spread in arid areas by shorelines wherein ground water is brackish and rainfall is rare. In spite of the popularity of these areas, construction of desalination plants to produce freshwater for tourists is not economical due to the briefness of the tourism season and decline of demand most of the year. Transportation of loads of freshwater is costly and exposes the water to contamination en route and during handling and storage. Reliance on bottled water is expensive for the average consumer while this source will not provide freshwater for other uses.
Accordingly, there is a compelling need for systems that can supply freshwater to cabins, camping areas and tourist areas while providing coolness indoors during tourism seasons in regions characterized by humid hot weather throughout.
Water quality in areas for which freshwater can be easily transported from water natural or man-made resources is often lower than the standards for drinking water quality due to exposure to contamination during handling, transport and storage in water tanks on top of buildings which forces the residents to use bottled water.
Accordingly, local water production from atmospheric humidity will reduce in the expenditure on drinking water and provide excess water for other human uses as long as the weather conditions are appropriate.
Prior art encompasses inventions that utilize chemical adsorbents to dry atmospheric air or moisture-laden gases. The moisture from air conditioning units is extracted as water for use whether as drinking water or fresh water after appropriate treatment. The adsorbent is regenerated and recycled for reuse. The use of adsorbents may be necessary in cases wherein insignificant amount of moisture is present in the atmosphere whereas in the case of extremely hot and humid environments the use of chemicals seems to be a nuisance and would require additional steps for extraction of water and regeneration of the chemicals.
3. Description of the Prior Art
U.S. Pat. No. 4,313,312, for example, discloses a water producing air conditioning system comprising a water producing apparatus that adsorbs moisture in the ambient air on an adsorbent or absorbent and evaporates water adsorbed on the adsorbent or absorbent by heating it and condenses steam to obtain water. A heat exchanger exchanges heat between ambient air and hot dry air discharged from the water producing system during adsorbing moisture on the adsorbent or absorbent. An evaporation-cooling system is used for forming a cold wet air by evaporating water and cooling it by contacting water with a dry air at the ambient temperature passed through the heat exchanger. The hot air heated by the heat exchanger or the cold air obtained from the evaporation-cooling system is utilized for the air conditioning. The system can be used for comfortable living in a severe condition such as a desert by the effective combination of the evaporation-cooling apparatus with the waterproducing device utilizing high efficiency heat-exchange.
This aforementioned invention and others that may fall under the same category do not relate to the present invention since they are based on the use of adsorbents, desiccants and hygroscopic material, and mostly address hot low humidity climate conditions; which is not of concern to the present invention.
Heat pipes are used in some inventions to cool a condensing surface to dew point to precipitate the water vapor from the atmosphere. Heat pipes are also used to control indoor environment. However, the present invention is not based on this type of technology exploitation and inventions using heat pipes to cool condensing surfaces to dew point to precipitate the water vapor from the atmosphere or to cool closed spaces differ from the present invention in the use of heat pipes.
The prior art has also encompassed processes that rely upon heat convection in large structures and the control of the process to obtain freshwater from atmospheric humidity.
Tropical and subtropical regions having high ambient temperatures and relative humidity can be locally subjected to cooling and dehumidification according to U.S. Pat. No. 4,182,132, in which a tower, upon a post or other vertically extending support, and a pair of vertically aligned spaced apart air guides are provided. The lower air guide includes the cooler that can simultaneously condense moisture from the air while the upper air guide can include a heat dissipater of a refrigeration cycle. The air guides are associated with blowers and inducing ambient air into the air guide at a location between them and displacing the air through the air guides into heat exchanging relationship. The tower can also be used to collect potable (drinking) water by condensation from the atmosphere.
The above inventions that rely upon heat convection in large structures in extraction of freshwater from the atmosphere and cooling or dehumidification of local open space do not relate to the present invention, which is based upon processes that are performed within compact structures.
Domestic central air conditioning units used to cool homes or any other buildings operate in combination with air directing units that produce a quantity of waste condensate. The water formed by condensation taken out of the air was utilized in a lawn watering system that was disclosed in U.S. Pat. No. 4,134,269. A device is designed for continually collecting the waste condensate from the central air conditioning unit. The water is stored in a holding tank. At a predetermined level in the tank, a pump is switched on to deliver the water to a hose system in the lawn. The system intermittently and automatically distributes the condensate throughout a region to be irrigated. The device comprises: a holding tank for collecting the waste condensate; a drainage conduit for directing the waste condensate from the air conditioning unit to the holding tank; a depth sensing device is used indicating the level of the waste condensate collected in the tank; a pump that is automatically turned on by the depth sensing device to pump collected waste condensate from the holding tank when the depth sensing device indicates that the level of condensate in the tank has reached a predetermined maximum and automatically turned off by the depth sensing device when the depth sensing device indicates that the level of condensate in the tank has reached a predetermined minimum thus allowing the condensate to refill the tank to the predetermined maximum level; a discharge conduit associated with the pump; and an irrigation system for directing the waste condensate from the holding tank throughout the region to be irrigated.
None of the prior art references that benefit from condensation capabilities of air conditioning or dehumidification discloses modifications of those units that enhance cooling while increasing of freshwater output of the units by condensation of outdoor atmospheric humidity. Since the benefits drawn are restricted to the use of the condensate and drainage that come from the units, the use is limited to watering of flower or rose beds, lawns and similar limited applications.
Furthermore, none of the prior inventions discloses devices or means for utilization of the mild temperature dry air that exits after removal of humidity from ambient air, with the exception of air conditioning units where extracted water is a secondary product of the air conditioning process.
In addition, the present invention relies to a great extent on gravity in collection of condensate and in the flow of freshwater.
According to the present invention, freshwater and drinking water are produced by modification of commercial air conditioning units of different sizes and capacities; used to cool ambient air inside closed spaces and buildings, wherein the cooling cycle includes a stage for condensation of water vapor carried by the indoor and outdoor air surrounding the unit. In a second aspect of the invention, different embodiments are presented to utilize the coolness of dry air immediately following the heat exchange process leading to condensation of water vapor and reducing air temperature in modified dehumidifiers. In a third aspect of the invention, combined modified air conditioning units and modified dehumidifiers or double dehumidifiers are used to provide air cooling as well as freshwater supply.
In adaptation of air conditioning and ventilation units, design and construction of equipment for water production from condensate depend on the type of unit and the way it is used. There are three basic types of air conditioning systems. Window-mounted units fit in a standard window opening with adequate support, but without modification to the window structure. Larger units are to be mounted in an opening in a wall. The size is not constrained except by the width of the wall and the weight is only limited by the permissible loading of the supporting structure. Both units are used to cool a room or a limited space. The third type is central air conditioning systems that cool a whole house, an apartment or an office building. Those are split in a manner that allows placement of the heavy components outside the buildings and hence there is no limitation on their size, capacity or weight. In all three systems, collection of condensate from the drippings of the condensation of the water vapor entrained in the air to supply varying quantities of freshwater is possible. However, the amount of water condensate that can be obtained from air conditioning equipment used for air-cooling and ventilation depends on the capacity of the equipment, the temperature setting inside the building and the temperature and relative humidity outside the building. Accordingly, the rate of condensation changes with the daily and seasonal variation of the local weather.
Air conditioning units are operated on three modes, air-cooling, ventilation and a combination of air-cooling and ventilation. In the air-cooling mode, the air conditioning unit operates as a closed system that cools indoor air with minimal male-up air drawn from the outdoors air. Outdoor air is drawn inside the closed space to freshen the air circulation indoors. In some systems, air cooling continues while the unit is switched to ventilation and hence outdoor air is cooled as it enters the unit, however, the cooling will not be efficient since the flow of air is blown fast to the inside of the space without recycling to reduce the temperature and condensate the water vapor entrained in the air.
Air conditioning units produce water whenever used for air-cooling under all weather conditions. Nevertheless, production of freshwater from air conditioning units operating on the cooling mode before appropriate modifications are made is very limited; compared to water production from dehumidifiers, since in air conditioning units humidity and temperature are substantially reduced after short periods of air cooling, since the inside air is re-circulated without too much opportunity to draw makeup air from the outdoors hot humid ambient air. However, the re-circulated air often contains additional humidity from evaporation of moisture from human bodies, breathing, and human activities. In case of meeting-halls or crowded spaces, high humidity will be continuously generated. In case of homes, cooking and preparation of hot drinks increase the level of humidity inside closed spaces. In some situations, the humidity loading of the air conditioning unit from re-circulated air can be higher than that from makeup air or outside air in case of operation on ventilation mode.
Accordingly, specific modifications are necessary prior to using commercial air conditioning units in production of freshwater; including the addition of a condensation unit to condensate outdoor humidity; that is a refrigerant evaporator working continuously regardless of whether the air conditioning unit is operating in an air-cooling mode, air heating mode, ventilation mode or a combined air-cooling and ventilation mode. Furthermore, the condensate drippings from the unit has to be collected when it cools air drawn from outdoors or re-circulates indoors humid air. However, the exposure of indoor air to bacteria, dust, viruses, microbes, and harmful volatile organic particulates requires the use of filters and disinfectants before adding the condensate to the water produced by the additional condensation stage since the collected water will be used for drinking. On the other hand, collection of the drippings from the air conditioning unit for other uses may not require extensive treatment.
In case of window-mounted units, one of the aspects of the invention provides appropriate modifications compatible with the rectangular geometry of a unit fitted to a standard window opening. This requires that any additional equipment must be light and small so that their size can fit within the standard dimensions of window used in the regions of applications and their weight can be supported without changing in the structure of the window. Furthermore, window-mounted units are of limited capacity which makes it difficult to collect adequate quantity of condensate for production of sufficient freshwater that justify the expense of collection equipment, since the humidity of the indoors air will decrease after short time form the start of unit operation. Considering those limitations, this aspect of the invention provides a design encompassing the addition of an external condensation stage outside the window to condensate water vapor entrained in the outdoors hot humid air and a water treatment unit inside the building to be placed directly under the air conditioning unit.
In case of wall-mounted units, there is more room to introduce modifications adequate for utilization of the humidity from outside air and collection of condensate from cooling of inside air. In this situation, collection of larger supply of freshwater can be achieved. In addition, freshwater equipment can be connected to dispensers in kitchens; for example, or in any other place appropriate for using the product water to supply drinking water or freshwater for other uses such as cooking, washing, preparation of foods and drinks, etc.
Space limitations can be almost entirely overcome in case of utilization of central air conditioning units typically used in buildings and large houses. In this case, unit modifications may include placing equipment necessary for collection of condensate water outside the building proper. In addition, special water condensation equipment can be installed outside the house or building to include several coils and finned flat surfaces for condensation of large quantities of water from water vapor entrained in outdoor hot humid ambient air or the construction of special high efficiency circular condensation units with extended finned surfaces. Furthermore, the water purification units for treatment of water for human consumption can be an integral part of the water supply system for the building.
Naturally, there is a potential for using air conditioning units in cars or other land and sea vehicles to produce a limited quantity of drinking water or freshwater by collecting the condensate from such units. However, the quantity will be limited by the space available to add support units or modify existing units.
In other aspects of the invention, several embodiments of systems and methods benefit from the capabilities of dehumidification equipment in drying humid air by condensation of water vapor entrained in hot humid ambient air inside closed spaces, in space cooling and in extraction of humidity to supply freshwater to meet daily water demand for different uses including drinking. This has been accomplished by the present invention, through providing units that can be mounted on windows or in a wall opening or as a central system. In case of adaptation of central dehumidification systems, water condensation and collection is placed inside the building to provide water and coolness while other components are placed outside the building, such as the refrigerant compressor and condenser when using conventional refrigeration cycles, since such components require space and cooling. In space dehumidifiers, cooling of those components is usually achieved by blowing the produced dry cooler air over them after passing by the water condensation unit. This is why dry air from space dehumidifiers exits at high temperatures.
In these aspects of the invention, different refrigeration cycles are used to condensate water vapor carried by ambient air while cooling air indoors; specifically thermo-acoustic cooling and thermoelectric cooling, which have several merits over conventional refrigerant cycles using CFC refrigerants. Equipment for these cycles occupy less space, do not require frequent replenishing of refrigerants and require minimal preventive maintenance compared to equipment using rotating equipment.
In a third aspect of the invention, combination of air conditioning units and dehumidification units is disclosed wherein modifications of these units allow efficient space cooling and production of freshwater. The indoor air cooling has the added benefits of using fresh outdoor air on continuous bases rather than circulating the indoor air with minimal make up air, leading to accumulation of pollutants in indoor air.
Accordingly, it is an object of the present invention to supply freshwater and treated drinking water in addition of air-cooling from air conditioning units of different sizes and capacities.
It is a second object of the present invention to modify air conditioning units; normally used in buildings of various living space areas and sizes to increase the production of water by condensation of outdoor humid hot ambient air during hot humid seasons.
It is a third object of the present invention to modify dehumidifiers and air dryers of different sizes to provide a comfortable level of coolness inside closed spaces while utilizing the condensated water vapor from hot humid air to produce freshwater.
It is a fourth object of the present invention to provide houses and buildings with systems to harvest freshwater for human consumption from hot humid ambient air while providing some moderate cooling inside without the need to transport water or acquiring it by external means and without the need for air conditioning units.
It is another object of the present invention to construct combined air cooling and air drying systems to efficiently cool indoor air while supplying fresh water for large buildings.